This invention relates to improved tamper evident container constructions including apparatus for forming such containers.
It has become increasingly important to provide tamper proof or tamper evident packaging for consumer related goods and particularly for medicinal products and foodstuffs. Recent history documents the tragic consequences which can occur when tampering with container contents goes unnoticed. It is, in fact, now required by law that at least certain pharmaceutical products be protected by in tamper proof packaging. The practical necessity for tamper proof or tamper evident packaging for non-medicinal products and particularly for packaged food items such as ice cream and other dairy products, as well as many other pre-prepared food products is readily apparent.
Numerous attempts have been made in the container industry and specifically with respect to consumer oriented foodstuffs, medicines, etc. to prevent potentially harmful tampering with the contents of such containers. It is well known, for example, to heat seal a thin foil disk about the container opening prior to application of the lid. This approach, while successful to a large extent, nevertheless involves the addition of another component to the assembly, i.e., the foil disk, and related assembly procedures and associated costs.
Other attempts to provide effective tamper proof mechanisms in container assemblies are well documented in the patent literature. U.S. Pat. No. 4,966,294, for example, discloses a tamper evident closure for a wide mouth container wherein rim segments are formed in the skirt portion of the container lid and are arranged so that upward lifting force applied against the lid flange will cause breakage to occur at opposite ends of the flange, and a continued upward pulling on the flange will results in a pair of tear lines in the lid to facilitate removal of the lid.
In U.S. Pat. No. 2,383,760, a closure for a container includes a flat upper surface in the peripheral depending skirt portion, around which is adhesively secured a strip which extends below the container flange and includes a bent marginal flange portion extending upwardly and inwardly from the bend. The flange is a continuous, smooth flange which, after insertion over the upper portion of the container, will snap into locking engagement with the flange. The marginal portion of the sealing strip is provided with a strip of adhesive so that the marginal portion will be cemented to the inside face of the container flange. No means are provided, however, for facilitating the easy removal of the closure. In fact, it is stated that when a container is opened, the cover will be disposed of, apparently because it will be damaged or destroyed in the opening operation.
In U.S. Pat. No. 1,955,865, container closures are disclosed which are formed with depending skirt portions and integral circumferentially spaced bent tab portions. These tab portions are designed to cooperate with complementary circumferentially spaced tabs formed on the periphery of the container side wall. Locking of the lid to the container is achieved by pressing the closure down over the tabs and rotating it so that the tabs will lie behind respective tabs on the container side wall. Fairly rigid disks are required to maintain the locking engagement between the cover and the container.
Other tamper proof constructions are disclosed in U.S. Pat. Nos. 3,044,610; 3,997,056 and 4,602,718.
These prior efforts are characterized by rather complex, and therefore costly, arrangements which are not fully satisfactory in all respects.
This invention provides a reliable and reusable tamper evident container construction particularly useful in the packaging of ice cream and other food products, as well as apparatus for forming such containers. The tamper evident lid in accordance with this invention is an improvement over the tamper evident lid disclosed in the above identified commonly owned '907 application.
In the latter application, the tamper evident lid comprises a paper or paperboard center disk which is roll seamed to a peripheral depending skirt. The depending skirt is formed from spiral wound paper stock and includes a line of perforations about the periphery of the skin, overlying the container rim, to define a removable tear strip. After the container is filled and lidded, the lower end of the peripheral skirt is curled radially inwardly under the container rim to thereby lock the lid in place. A tear or gripping tab provided in the tear strip allows the user to separate the tear strip from the lid thereby enabling the lid to be removed from the container. At the same time, once the tear strip has been removed, the fact of its removal is readily apparent from visual inspection, so that any tampering with the container contents via removal and subsequent replacement of the lid is immediately evident.
In this continuation-in-part application, the peripheral skirt of the lid is formed of at least two and preferably three layers of spiral wound paper stock and a fourth outer printing layer (i.e., a relatively thin paper layer). This construction has been found necessary in order to provide the required column strength for the peripheral skirt during the curling operation. In this improved version of the lid, the three layers of spiral wound stock are arranged so that the spiral seams are staggered, one relative to the other. As a result of this three-ply (four layer) construction, the necessary strength is achieved while permitting greater tolerance in the spiral seam gaps of the respective spiral wound stock layers.
This continuation-in-part application also relates to apparatus which may be employed to secure the tamper evident lid on an associated, filled container in such a way that the locking curl and the gripping tab are formed simultaneously. In a first exemplary embodiment of the apparatus, a conventional Flex-E-Fill.RTM. container filling machine including a turntable which indexes individual containers, one at a time through a filling and lidding station, has been modified to incorporate a new die press head for securing the tamper evident lid of this invention to a filled container while simultaneously forming a gripping tab in the removable tear strip portion of the lid.
There is also provided in this first exemplary embodiment, an alignment mechanism which rotates the container to a predetermined orientation so that printed matter relating to the manner in which the tear strip is to be removed will be properly aligned on the container side wall in proximity to the gripping tab on the lid. More specifically, the filed container is initially indexed past an alignment mechanism which includes a rotatable arm which engages the peripheral side wall of the container. This arm is caused to rotate through a full 360.degree., finding and engaging the container side wall seam during its rotation, and by engaging the seam, causing the container to rotate through the balance of the 360.degree. to thereby locate the seam in a predetermined orientation. After receiving a lid, the container/lid assembly is thereafter indexed to the lid die press station where each container is raised up into the die head. Split, segmented dies are then closed and pulled upwardly to curl or tuck the depending peripheral skirt portion of the lid around the lower edge of the container rim. The segmented dies form a substantially continuous curling annulus when closed, except for a minor portion of the circumference where the curling surface is omitted so as to leave an untucked or uncurled portion which forms the gripping tab for removing the tear strip. A slitting knife is also provided in this area of the segmented dies to form a vertical slit in the depending skirt where the curled portion interfaces with the uncurled portion. This slit defines an edge of the gripping tab which allows the latter to be easily pulled by the user to remove the tear strip from the lid.
After the lid has been secured to the container as described above, the segmented dies open in a radial direction allowing the container to be lowered back to its original level, and the lidded container is then indexed out of the machine and transferred passed onto a conveyor.
In a second exemplary embodiment of the apparatus, a multi-head machine is provided which receives already filled and lidded containers in a continuous operation, and which automatically secures each container lid to its associated container. In this second exemplary embodiment, a turntable is provided with eight die press heads which are similar in every respect to the die press heads utilized in the earlier described embodiment. In this second exemplary embodiment, however, the speed with which the container lids are secured to their associated containers is greatly increased by reason of the continuous operation of the machine and the use of a plurality of die press heads. This second exemplary embodiment also utilizes an alignment mechanism for rotating the containers to a predetermined orientation in a manner similar to the earlier described embodiment, although utilizing slightly different mechanical components reflecting the continuous nature of the multi-head machine. The alignment mechanisms for both exemplary embodiments will be described in further detail herein.
Accordingly, this invention in its broader aspects relates to a tamper evident lid for use with a container including a container body having a bottom wall and a peripheral side wall, the side wall terminating in an outwardly curled rim, the lid comprising a top wall and a depending skirt having upper and lower ends, the depending skin secured at the upper end to the top wall, wherein the depending skin is constructed from at least two layers of spiral wound paper stock, each having a spiral seam offset circumferentially relative to each other.
In another aspect, the invention relates to a tamper evident container assembly comprising a container body having a bottom wall and peripheral side wall, the side wall terminating in an outwardly curled rim; a reusable lid having a top wall portion and a depending skin portion, the depending skirt portion constructed of spiral wound stock and having a free end, a major peripheral portion of the free end tucked under the upper rim and upwardly into engagement with the side wall, between the side wall and the rim, a minor peripheral portion of the free end is left untucked to thereby provide a gripping area to facilitate tearing and removal of the tear strip, the skirt portion including the tucked portion being in substantially continuous engagement with the rim to thereby lock the lid to the container body; wherein the depending skirt portion is further provided in a lower portion thereof with a line of weakening extending annularly about the skirt portion to thereby define an annular removable tear strip inclusive of the free end, the line of weakening lying on the rim, between upper and lower edges of the rim.
In another aspect, the invention relates to apparatus for securing a tamper evident lid to a container wherein the lid includes a depending skirt portion and the container includes a rim at an upper open end thereof, the apparatus comprising:
a) first means for pressing a lower portion of the depending skirt portion of the lid under and into engagement with the rim of the container to form a curl about a major peripheral portion of the lid while leaving a minor peripheral portion uncurled; and PA1 b) second means cooperating with the first means for simultaneously forming a vertical slit in the lower portion of the depending skirt portion at an interface between the curled and uncurled portions to thereby form a gripping tab therein.
The above described invention thus provides a novel, tamper evident lid construction and associated apparatus for securing the tamper evident lid to a container in a relatively simple and economical manner to provide a high quality, tamper evident lid/container assembly which safeguards the user against potentially harmful tampering.